Revert of Move fetching logic out of ApplicationManager, eliminate url mappings.

mojo/fetcher/update_fetcher.h

-// Copyright 2015 The Chromium Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style license that can be
-// found in the LICENSE file.
-
-#ifndef MOJO_FETCHER_UPDATE_FETCHER_H_
-#define MOJO_FETCHER_UPDATE_FETCHER_H_
-
-#include "mojo/shell/fetcher.h"
-
-#include "base/files/file_path.h"
-#include "base/memory/weak_ptr.h"
-#include "mojo/services/updater/updater.mojom.h"
-#include "url/gurl.h"
-
-namespace mojo {
-
-class URLLoaderFactory;
-
-namespace fetcher {
-
-class UpdateFetcher : public shell::Fetcher {
- public:
-  UpdateFetcher(const GURL& url,
-                updater::Updater* updater,
-                const FetchCallback& loader_callback);
-
-  ~UpdateFetcher() override;
-
- private:
-  // Fetcher implementation:
-  const GURL& GetURL() const override;
-  GURL GetRedirectURL() const override;
-  GURL GetRedirectReferer() const override;
-  URLResponsePtr AsURLResponse(base::TaskRunner* task_runner,
-                               uint32_t skip) override;
-  void AsPath(
-      base::TaskRunner* task_runner,
-      base::Callback<void(const base::FilePath&, bool)> callback) override;
-  std::string MimeType() override;
-  bool HasMojoMagic() override;
-  bool PeekFirstLine(std::string* line) override;
-
-  void OnGetAppPath(const mojo::String& path);
-
-  const GURL url_;
-  base::FilePath path_;
-  base::WeakPtrFactory<UpdateFetcher> weak_ptr_factory_;
-
-  DISALLOW_COPY_AND_ASSIGN(UpdateFetcher);
-};
-
-}  // namespace fetcher
-}  // namespace mojo
-
-#endif  // MOJO_FETCHER_UPDATE_FETCHER_H_